from typing import *


class Solution:

    def findChampion(self, n: int, edges: List[List[int]]) -> int:
        ins = [0] * n
        for a, b in edges:
            ins[b] += 1
        ans = -1
        for i, v in enumerate(ins):
            if v == 0:
                if ans == -1:
                    ans = i
                else:
                    return -1
        return ans
